The aliphatic amine polymer is a cross-linked polyallylamine with a pharmaceutically acceptable acid. The aliphatic amine polymer is an epichlorohydrin-cross-linked polyallylamine with a pharmaceutically acceptable acid, such as sevelamer, sevelamer hydrochloride, colesevelam or its hydrochloride salt.
The colesevelam hydrochloride is a non-absorbable, polymeric and a high-capacity bile acid-binding molecule. It is also a lipid-lowering and glucose-lowering agent intended for oral administration. Colesevelam hydrochloride is poly (allylamine hydrochloride) cross-linked with epichlorohydrin and alkylated with 1-bromodecane and (6-bromohexyl)-trimethylammonium bromide. Colesevelam hydrochloride is hydrophilic and insoluble in water. Chemically, allylamine polymer with 1-chloro-2,3-epoxypropane, [6-(allylamino)-hexyl]trimethylammonium chloride and N-allyldecylamine, hydrochloride and is represented by the following formula:

In the structure, m represents a number ≧100 to indicate an extended polymer network.
Colesevelam hydrochloride is approved in United States under the proprietary name Welchol® as oral tablet and marketed by Daiichi Sankyo.
Welchol® is indicated as an adjunct to diet and exercise to reduce elevated low-density lipoprotein cholesterol (LDL-C) in adults with primary hyperlipidemia (Fredrickson Type IIa) as monotherapy or in combination with HMG CoA) reductase inhibitor (statin) and as an adjunct to diet and exercise to improve glycemic control in adults with type 2 diabetes mellitus.
U.S. Pat. No. 7,229,613 discloses a method for treating hyperglycemia and/or reducing serum glucose levels in a patient that includes administering to the patient a therapeutically effective amount of colesevelam or salts thereof.
U.S. Pat. No. 6,733,780 discloses a compressed tablet comprising a hydrophilic core comprising at least or about 95 weight % of poly (allylamine) or a salt thereof and a water-based coating comprising cellulose derivative and plasticizing agent. The patent discloses coating composition comprising hydroxypropylmethylcellulose and a plasticizer. The disclosed coating composition contains at least 23% of diacetylated monoglyceride as a plasticizing agent.
The U.S. Patent Application No. 2010/0008988 discloses pharmaceutical compositions comprising less than about 95% by weight of aliphatic amine polymers of sevelamer hydrochloride, sevelamer carbonate and colesevelam hydrochloride, and methods of preparing pharmaceutical compositions thereof.
The U.S. Patent Application No. 2010/0330175 discloses a pharmaceutical composition comprising dry cross-linked polyallylamine and water soluble excipient comprising polyols and polyethylene glycol.
The U.S. Patent Application No. 2011/0159087 discloses a pharmaceutical composition comprising wet granulated bile acid sequestrants composition, wherein the composition is free of reducing sugar.
The colesevelam hydrochloride tends to be very hygroscopic and thus will swell immediately upon contact with the inside of the mouth. Thus it was believed that coating such tablets with aqueous based coating would be difficult because the hygroscopic tablets would swell during the coating process.
The prior arts disclosure suggests that use of a relatively high amount of diacetylated monoglyceride as plasticizing agent in coating composition to overcome the tablet-swelling problem and to stabilize the pharmaceutical compositions of poly allylamines or a salt thereof.
Thus, there still exists an enduring need to develop an improved and stable pharmaceutical composition of aliphatic amine polymers which will provides an alternative to existing formulation of colesevelam hydrochloride.